JP2017145907A - Pilot valve device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pilot valve device which has a casing made compact and lightweight.SOLUTION: A casing 2 internally has a spool slide hole 6 extending along a length, and is provided with a pump port 3, a tank port 4, and an output port 5 apart from one another in a length direction of the spool slide hole 6. In the spool slide hole 6, a spool 20 which links the output port 5 to one of the pump port 3 and the tank port 4 is provided to slide. On the other length-directional side of the spool slide hole 6, a dumping chamber 6A is provided which communicates with the tank port 4 through a first passage 23A having a throttle 24. The spool 20 is provided with a first changeover part 25 which links and blocks the pump port 3 and output port 5, and a second changeover part 26 which links and blocks the tank port 4 and the output port 5. The second changeover part 26 is provided at a position closer to the dumping chamber 6A than the first changeover part 25.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pressure reducing valve type pilot valve device which is provided in a construction machine such as a hydraulic excavator and is suitable for switching a direction control valve by a pilot pressure.

  Generally, a construction machine such as a hydraulic excavator is provided with an operation lever device on each of the left and right sides of a driver's seat, and the operation lever device includes a plurality of pressure reducing valves that output pilot pressure according to the tilting operation of the operation lever. A pilot valve device using a type of pilot valve is provided.

  These pilot valve devices are connected to directional control valves for turning, boom, arm, and bucket via pilot piping or the like. These directional control valves for turning, boom, arm, and bucket are switch-controlled by pilot pressure from a pilot valve device.

  For example, the directional control valve for the arm and the directional control valve for turning are controlled by operating the left operating lever, and the directional control valve for the boom and the bucket are controlled by operating the right operating lever. The directional control valve is controlled.

  This pilot valve device has a spool sliding hole extending in the length direction, a casing provided with a pump port, a tank port and an output port spaced apart in the length direction of the spool sliding hole, A spool that is displaceably provided in the spool sliding hole and that communicates the output port with either the pump port or the tank port, and is disposed on one side in the longitudinal direction of the spool so as to be displaceable in the casing. And a pusher that slides and displaces the spool by an external pressing operation.

  In this case, when the pusher is pressed, the spool is slid downward, the output port communicates with the pump port, and the pressure oil (pilot pressure) from the pilot pump is discharged to the output port. The hydraulic excavator is configured to rotate, drive a boom, and the like (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-318206

  By the way, in the above-described prior art, a damping chamber for applying fluid pressure to the end face of the spool is provided on the bottom side of the spool sliding hole in order to suppress the fluctuation of the spool due to the vibration of the excavator.

  However, since the damping chamber is provided, the output port has to be shifted in the lateral direction. As a result, there is a problem that the casing is enlarged by an amount corresponding to the extension of the output port.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a pilot valve device which is intended to reduce the size and weight of a casing.

  A pilot valve device according to the present invention has a spool sliding hole extending in the length direction, and a casing provided with a pump port, a tank port and an output port spaced apart in the length direction of the spool sliding hole, A spool that is displaceably provided in a spool sliding hole of the casing and communicates the output port with either the pump port or the tank port, and is positioned on one side in the length direction of the spool and can be displaced to the casing. And a pusher that slides and displaces the spool by a pressing operation from the outside, and fluid pressure is applied to the end surface of the other side in the length direction of the spool on the other side in the length direction of the spool. A damping chamber is provided, which is connected to the tank port through a flow passage having a throttle. The spool is provided with a first switching unit for communicating and blocking the pump port and the output port, and a second switching unit for communicating and blocking the tank port and the output port, and the second switching unit. The switching unit is provided at a position closer to the damping chamber than the first switching unit.

  According to the present invention, the cost can be reduced by reducing the size and weight of the casing.

It is a front view which shows the pilot valve apparatus by the 1st Embodiment of this invention. It is sectional drawing which looked at the pilot valve apparatus from the arrow II-II direction in FIG. It is sectional drawing which looked at the pilot valve apparatus from the arrow III-III direction in FIG. It is sectional drawing which looked at the pilot valve apparatus from the arrow IV-IV direction in FIG. It is sectional drawing which looked at the pilot valve apparatus from the arrow VV direction in FIG. It is sectional drawing which looked at the pilot valve apparatus from the arrow VI-VI direction in FIG. It is sectional drawing similar to FIG. 3 which shows the pilot valve apparatus by the 2nd Embodiment of this invention. It is sectional drawing similar to FIG. 3 which shows the pilot valve apparatus by the 3rd Embodiment of this invention.

  Hereinafter, a pilot valve device according to the present invention will be described with reference to the accompanying drawings.

  1 to 6 show a first embodiment of the present invention. A pilot valve device 1 shown in FIG. 1 is used, for example, in an operating device for excavating a hydraulic excavator (not shown), and performs a switching operation of a direction control valve by a pilot pressure. The pilot valve device 1 includes a casing 2 constituting a main body and four pilot valves 18 accommodated in the casing 2.

  In the casing 2, a pump port 3 into which pressure oil from a hydraulic pump (not shown) serving as a pilot hydraulic power source flows, a tank port 4 that is always in communication with a tank (not shown), and a direction on the main circuit side Four output ports 5 connected to a switching valve (not shown) are provided. The pump port 3, the tank port 4 and the output port 5 are provided apart in the length direction of a spool sliding hole 6 which will be described later.

  As shown in FIG. 3, the pump port 3 includes a pump port connecting portion 3A that is located at the center of the casing 2 and connected to a hydraulic pipe (not shown), and a pump that extends upward from the pump port connecting portion 3A. The port oil passage 3 </ b> B and the pump port chamber 3 </ b> C communicated with each spool sliding hole 6, which will be described later, in addition to the pump port oil passage 3 </ b> B.

  As shown in FIGS. 3 and 4, the tank port 4 includes a tank port connection portion 4 </ b> A that is located outside a spool sliding hole 6, which will be described later, and is connected to a tank conduit (not shown), and the tank port connection portion. The tank port oil passage 4B extends upward from 4A, and the tank port chamber 4C communicates with the tank port oil passage 4B and communicates with each spool sliding hole 6 via a spring chamber 9 described later. Yes.

  Each output port 5 is located at each of the four corners of the casing 2 and is adjacent to each spool sliding hole 6 described later. Each output port 5 communicates with an output port connecting portion 5A connected to a pilot pipe (not shown), an output port oil passage 5B extending upward from the output port connecting portion 5A, and an output port oil passage 5B. The annular output port chamber 5C communicates with a spool sliding hole 6 to be described later.

  The spool sliding hole 6 is provided in the casing 2 so as to extend in the length direction (upward and downward). For example, four spool sliding holes 6 are provided, and a spool 20 described later is slidably inserted therein. The lower end side of the spool sliding hole 6 is a damping chamber 6A. The damping chamber 6A communicates with the tank port 4 via a first passage 23A having a throttle 24 described later. The damping chamber 6A applies fluid pressure to the lower end surface of the spool 20 described later. As a result, the damping chamber 6 </ b> A provides a damping force that reduces the vibration of the spool 20 together with the throttle 24.

  On the other hand, the upper end side of the spool sliding hole 6 communicates with the tank port chamber 4C of the tank port 4 via a spring chamber 9 described later. Further, the output port chamber 5C of the output port 5 communicates with the spool sliding hole 6 at a position close to the damping chamber 6A, and the pump port 3 at an intermediate position between the tank port chamber 4C and the output port chamber 5C. The pump port chamber 3 </ b> C communicates with the spool sliding hole 6. That is, the pump port chamber 3C, the tank port chamber 4C, and the output port chamber 5C are arranged in the order of the spool port 4C, the pump port chamber 3C, and the output port chamber 5C from the top in the length direction of the spool slide hole 6. 6 communicates.

  On the upper end side of the casing 2, a bottomed female screw portion 7 is provided at the center thereof. A mounting member 14 to be described later is screwed into the female thread portion 7. Further, around the female screw portion 7, four bushing attachment holes 8 to which a bushing 15 described later is attached are provided. A spring chamber 9 is provided between the spool sliding hole 6 and the bushing mounting hole 8. The spring chamber 9 is provided with a pressure setting spring 27 and a return spring 29 which will be described later.

  The operation lever 10 is tilted by an operator. The operation lever 10 is disposed in a cab (not shown) of a construction machine such as a hydraulic excavator. The operation lever 10 includes a rod-shaped lever main body 11, a cam 12 integrally fixed to the lever main body 11, a connecting portion 13 made of a cross joint and the like, and an attachment screwed to the female screw portion 7 of the casing 2. It is comprised from the member 14 grade | etc.,. In this case, the base end side of the lever main body 11 is connected to the attachment member 14 via the connecting portion 13 so as to be swingable.

  Here, the cam 12 protrudes radially outward from the base end side of the lever main body 11, and the lower surface side thereof is in contact with the upper end (protruding end) side of each pusher 19 described later. Then, the cam 12 tilts according to the tilting operation with respect to the operation lever 10, thereby pressing each pusher 19.

  The bushing 15 is formed in a substantially cylindrical shape and is fitted in the bushing mounting hole 8 of the casing 2. A pusher 19 to be described later is slidably fitted on the inner peripheral side of the bushing 15. The bushing 15 is configured as a bearing member for the pusher 19.

  The seal member 16 is formed in an annular shape, and is disposed between the bushing 15 and the pusher 19 in a state where the seal member 16 is mounted in a circumferential groove formed in the bushing 15. While preventing intrusion, the oil in the casing 2 is prevented from leaking outside. The upper lid 17 covers the upper end side of the casing 2. The upper lid 17 holds the bushing 15 inserted into the bushing mounting hole 8 of the casing 2 in a state of being prevented from being removed.

  The pilot valve 18 includes a pusher 19, a spool 20, and a pressure setting spring 27. The pilot valve device 1 includes, for example, four pilot valves 18 in order to perform a turning operation and an arm operation of a hydraulic excavator (not shown). Since each pilot valve 18 has the same structure, only the configuration of one pilot valve 18 will be described below.

  The pusher 19 is slidably provided on the bushing 15, and is slidably provided on the casing 2. The pusher 19 is located on the upper end side (one side) in the length direction of the spool 20 to be described later, and slides and displaces the spool 20 by an external pressing operation. Specifically, the upper end side of the pusher 19 protrudes from the casing 2, and the protruding end is in contact with the lower surface of the cam 12. When the operation lever 10 is tilted, the pusher 19 is pushed downward by the cam 12, and the spool 20 is displaced downward following this.

  The spool 20 is provided in the spool sliding hole 6 so as to be displaceable. When the spool 20 is pressed by the pusher 19, the output port 5 communicates with either the pump port 3 or the tank port 4. The spool 20 includes a small-diameter portion 21 that extends into the spring chamber 9 and a large-diameter portion 22 that is connected to the small-diameter portion 21 and is slidably inserted into the spool sliding hole 6. . Further, the boundary between the small diameter portion 21 and the large diameter portion 22 forms a step surface, and this step surface is configured as a spring seat 20A of a pressure setting spring 27 described later.

  The large-diameter portion 22 includes an annular first land 22A located on the upper end side, an annular second land 22B located on the intermediate portion, and first and second lands 22A and 22B located on the lower end side. An annular third land 22C having a smaller outer diameter is formed. The first land 22 </ b> A always blocks between the pump port 3 and the tank port 4. The second land 22B communicates and blocks the pump port 3 and the output port 5 according to the axial displacement of the spool 20. That is, when the spool 20 is pressed by the pusher 19 and the second land 22B is positioned in the output port chamber 5C of the output port 5 over the entire length in the length direction, the first land 22A is discharged from the pump port 3. The oil liquid flows through the output port 5 through an annular groove between the first land 22B and the second land 22B. In this case, the second land 22B constitutes a first switching unit 25 described later.

  The third land 22C communicates and blocks the output port 5 and the tank port 4 via a second passage 23B described later according to the axial displacement of the spool 20. That is, for example, when the spool 20 is in the neutral position (position in FIG. 3) and when the spool 20 is slidably displaced in the axial direction, the third land 22C is output from the output port 5 over the entire length in the length direction. A second passage 23B, which will be described later, is located in the port chamber 5C and communicates with the output port chamber 5C. In this case, the third land 22C constitutes a second switching unit 26 described later together with the second passage 23B.

  The spool 20 is formed such that the outer diameter of the portion of the third land 22C is smaller than the outer diameters of the portions of the first land 22A and the second land 22B. As a result, a pressure receiving area difference is generated between the second land 22B and the third land 22C. Therefore, the feedback pressure when the spool 20 is pressed by the pusher 19 and the inside of the output port 5 is in a high pressure state acts on the second land 22B. For this reason, the spool 20 can be slid and displaced axially upward against a spring load of a pressure setting spring 27 described later.

  A passage 23 extending in the axial direction and the radial direction of the large diameter portion 22 is formed in the large diameter portion 22. The passage 23 has a first passage 23A as a flow passage having an upper end side (one side) communicating with the tank port 4 and a lower end side (other side) communicating with the damping chamber 6A, and the first passage 23A. And a second passage 23 </ b> B capable of communicating with the output port chamber 5 </ b> C of the output port 5. Thereby, the output port 5 can be communicated with the tank port 4 according to the position of the spool 20. In addition, a throttle 24 is provided on the lower end side of the first passage 23A to limit the flow rate of the oil liquid from the damping chamber 6A to the first passage 23A.

  Next, the first switching unit 25 and the second switching unit 26 of the spool 20 will be described.

  That is, the spool 20 is provided with a first switching unit 25 for communicating and blocking the pump port 3 and the output port 5 and a second switching unit 26 for communicating and blocking the tank port 4 and the output port 5. Yes. In this case, the 1st switching part 25 is comprised by the 2nd land 22B. On the other hand, the second switching unit 26 includes a third land 22C and a second passage 23B.

  As shown in FIG. 3, the second switching unit 26 is provided at a position closer to the damping chamber 6 </ b> A than the first switching unit 25. That is, the pump port chamber 3C of the pump port 3, the tank port chamber 4C of the tank port 4, and the output port chamber 5C of the output port 5 are arranged in the length direction of the spool sliding hole 6 from above (the pusher 19 side). The chamber 4C, the pump port chamber 3C, and the output port chamber 5C are communicated with the spool sliding hole 6 in this order. The tank port chamber 4C and the output port chamber 5C can communicate with each other by the first passage 23A and the second passage 23B in the spool 20.

  Therefore, by providing the second switching unit 26 below the first switching unit 25 (on the damping chamber 6A side), the length dimension (axial dimension) of the output port oil passage 5B of the output port 5 can be reduced. It can be made shorter than the output port oil passage of the output port in the pilot valve device. As a result, the height of the casing 2 can be reduced (cut by shaving) by the dimension A, so that the pilot valve device 1 can be reduced in size and weight.

  The pressure setting spring 27 is located in the spring chamber 9 and provided between the pusher 19 and the spool 20. The upper end portion of the pressure setting spring 27 is brought into contact with a spring seat 28 provided on the lower side of the pusher 19, and the lower end portion of the pressure setting spring 27 is locked to the spring seat 20A. The pressure setting spring 27 sets the discharge pressure from the output port 5 in accordance with the pressing operation of the pusher 19.

  The return spring 29 is provided on the outer peripheral side of the pressure setting spring 27. The return spring 29 has an upper end abutted against the spring seat 28 and a lower end abutted against the bottom of the spring chamber 9. The return spring 29 constantly urges the pusher 19 upward in the axial direction via the spring seat 28 in order to return the pusher 19 to the initial position.

  The pilot valve device 1 according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  First, when the operation lever 10 is in the neutral position (initial position), the first switching portion 25 (second land 22B) of the spool 20 blocks the pump port 3 and the output port 5, and the second switching portion 26 ( Since the third land 22C and the second passage 23B) connect the tank port 4 and the output port 5, the output port 5 is placed in a low pressure state. As a result, the direction switching valve of the main circuit is held in the neutral position.

  Next, when the operator tilts the operation lever 10, the cam 12 tilts with the connecting portion 13 as a fulcrum, thereby pushing the pusher 19 downward in the axial direction, and according to the amount of pressing operation at this time, the spool 20 is slidably displaced axially downward via the pressure setting spring 27. As a result, the first switching portion 25 (second land 22B) of the spool 20 allows the pump port 3 and the output port 5 to communicate with each other, and the second switching portion 26 (third land 22C and second passage 23B). The tank port 4 and the output port 5 are shut off.

  As a result, the output port 5 is placed in a high pressure state, and the pressure in the output port 5 acts on the second land 22B of the spool 20 as a feedback pressure. Therefore, the spool 20 slides and displaces upward in the axial direction against the spring load of the pressure setting spring 27. At this time, the pressure setting spring 27 is compressed and bent from the preset state.

  Then, when the first switching unit 25 of the spool 20 again shuts off the pump port 3 and the output port 5 and the second switching unit 26 connects the output port 5 and the tank port 4, the pressure in the output port 5 Therefore, the pressure setting spring 27 is extended from the compressed state, and the spool 20 is again slid downward in the axial direction by the spring load of the pressure setting spring 27. As a result, the first switching unit 25 of the spool 20 causes the pump port 3 and the output port 5 to communicate with each other, and the second switching unit 26 blocks the tank port 4 and the output port 5. Rises.

  That is, a spring load corresponding to the pressing operation amount with respect to the pusher 19 is generated in the pressure setting spring 27, and the pressure in the output port 5 is controlled corresponding to this spring load. Thereby, a pilot pressure corresponding to the operation amount of the operation lever 10 is supplied to the direction switching valve in the main circuit, and the direction control valve is neutral with a stroke amount corresponding to the pressure (pilot pressure) in the output port 5. The position is switched to the switching position.

  As a result, each hydraulic cylinder connected to the main circuit, an actuator such as a swing motor (not shown) can be operated at an operating speed corresponding to the operation amount of the operation lever 10, An arm, a bucket, or the like can be rotated (up and down), or the upper swing body can be rotated.

  By the way, in the above-described prior art, a damping chamber for applying fluid pressure to the end face of the spool is provided on the bottom side of the spool sliding hole in order to suppress the fluctuation of the spool due to the vibration of the excavator.

  However, by providing this damping chamber, the output port must be shifted laterally. In addition, the arrangement of each port is communicated with the spool sliding hole from the top (pusher side) in the order of the tank port, the output port, and the pump port. As a result, there is a problem that the oil passage of the output port becomes long and the casing becomes large. In addition, since the pump port is arranged above the damping chamber, oil leaks from the pump port to the damping chamber through the gap between the spool and the spool sliding hole, making the spool damper effect unstable. There is a risk of becoming.

  Therefore, in the present embodiment, the ports 3, 4 and 5 are communicated with the spool sliding hole 6 in the order of the tank port 4, the pump port 3 and the output port 5 from the top. The tank port 4 and the output port 5 can communicate with each other through the first passage 23A and the second passage 23B in the spool 20. That is, the second switching unit 26 that connects and disconnects the tank port 4 and the output port 5 of the spool 20 is closer to the damping chamber 6A than the first switching unit 25 that connects and disconnects the pump port 3 and the output port 5. Provided.

  Thereby, the length dimension of the output port oil passage 5B of the output port 5 can be made shorter than the output port oil passage in the conventional pilot valve device. Accordingly, since the height of the casing 2 can be reduced by the dimension A (cutting), the pilot valve device 1 including the damping chamber 6A can be reduced in size and weight, and the cost can be reduced. In addition, by reducing the size and weight of the pilot valve device 1, for example, the periphery of the driver's seat of the hydraulic excavator can be widened, so that the comfortability can be improved. The damping chamber 6A communicates with the tank port 4 via the first passage 23A and is separated from the pump port chamber 3C. Therefore, it is possible to reduce the leakage of the oil liquid from the pump port chamber 3C to the damping chamber 6A, so that a stable damper performance can be obtained in the spool 20.

  Next, FIG. 7 shows a second embodiment of the present invention. A feature of the present embodiment is that a casing side passage 35 capable of communicating the tank port 4 and the output port 5 is provided. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The spool 31 is provided in the spool sliding hole 6 so as to be displaceable. The spool 31 includes a small-diameter portion 32 and a large-diameter portion 33 as in the spool 20 according to the first embodiment. Further, the boundary between the small diameter portion 32 and the large diameter portion 33 is a spring seat 31 </ b> A of the pressure setting spring 27.

  The large-diameter portion 33 includes an annular first land 33A located on the upper end side, an annular second land 33B located on the intermediate portion, and an annular first land 33B located below the second land 33B. 3 lands 33 </ b> C and an annular fourth land 33 </ b> D located on the lower end side are formed. The first land 33 </ b> A always closes between the pump port 3 and the tank port 4. The second land 33 </ b> B connects the pump port 3 and the output port 5 in accordance with the position of the spool 31. In this case, the second land 33B constitutes a first switching unit 36 described later. The third land 33 </ b> C allows the output port 5 and the tank port 4 to communicate with each other via a casing-side passage 35, which will be described later, according to the position of the spool 31. In this case, the third land 33 </ b> C constitutes the second switching unit 37.

  The spool 31 is formed such that the outer diameters of the third land 33C and the fourth land 33D are smaller than the outer diameters of the first land 33A and the second land 33B. Thus, the feedback pressure when the spool 31 is pressed by the pusher 19 and the inside of the output port 5 is in a high pressure state is applied to the second land 33B, and the spool 31 is used as the spring load of the pressure setting spring 27. It can be slid and displaced axially upward.

  A spool-side passage 34 extending in the axial direction and the radial direction of the large-diameter portion 33 is formed in the large-diameter portion 33. The spool-side passage 34 is closed at the upper end side (one side) and has a lower end side (the other side) communicated with the damping chamber 6A, a first spool-side passage 34A, and the spool-side first passage 34A. This is formed by a spool-side second passage 34B capable of communicating with the casing-side second passage 35B. In addition, a throttle 24 is provided on the lower end side of the spool-side first passage 34A to limit the flow rate of the oil liquid from the damping chamber 6A to the spool-side first passage 34A.

  The casing side passage 35 extends in the casing 2 in the axial direction and the radial direction, and connects the tank port 4 and the spool sliding hole 6. Four casing side passages 35 are formed corresponding to the spool sliding holes 6. The casing side passage 35 has a casing side first passage 35A whose upper end side communicates with the tank port 4 and extends upward and downward (axial direction) along the spool sliding hole 6, and one side is the casing side first. The second passage 35 </ b> B communicates with the lower end side of the passage 35 </ b> A and the other side communicates with the spool sliding hole 6. In this case, the spool side passage 34 and the casing side passage 35 constitute a flow path of the present invention.

  Next, the first switching unit 36 and the second switching unit 37 of the spool 31 will be described.

  The spool 31 is provided with a first switching unit 36 for communicating and blocking the pump port 3 and the output port 5 and a second switching unit 37 for communicating and blocking the tank port 4 and the output port 5. In this case, the 1st switching part 36 is comprised by the 2nd land 33B. On the other hand, the second switching unit 37 is configured by a third land 33C.

  As shown in FIG. 7, the second switching unit 37 is provided at a position closer to the damping chamber 6 </ b> A than the first switching unit 36. That is, the pump port chamber 3C of the pump port 3, the tank port chamber 4C of the tank port 4, and the output port chamber 5C of the output port 5 are arranged in the length direction of the spool sliding hole 6 from above (the pusher 19 side). The chamber 4C, the pump port chamber 3C, and the output port chamber 5C are communicated with the spool sliding hole 6 in this order. The tank port chamber 4 </ b> C and the output port chamber 5 </ b> C can communicate with each other through a casing-side passage 35 in the casing 2.

  Thus, also in the pilot valve device according to the second embodiment, the length dimension of the output port oil passage 5B of the output port 5 is made shorter than the length dimension of the output port oil passage of the output port in the conventional pilot valve device. be able to. Accordingly, since the height of the casing 2 can be reduced by the dimension A (cutting), the pilot valve device 1 including the damping chamber 6A can be reduced in size and weight, and the cost can be reduced. In addition, by reducing the size and weight of the pilot valve device 1, for example, the periphery of the driver's seat of the hydraulic excavator can be widened, so that the comfortability can be improved.

  The damping chamber 6A communicates with the tank port 4 via the spool side passage 34 and the casing side passage 35, and is separated from the pump port chamber 3C. Therefore, it is possible to reduce the leakage of the oil liquid from the pump port chamber 3C to the damping chamber 6A, so that a stable damper performance can be obtained in the spool 31.

  Next, FIG. 8 shows a third embodiment of the present invention. A feature of this embodiment is that a filter 41 is provided in the pump port 3. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The filter 41 is detachably provided on the pump port connection 3 </ b> A of the pump port 3. The filter 41 is provided with a threaded portion 41A on the outer peripheral side, and the male threaded portion 41A is attached to the pump port connecting portion 3A by being screwed into the pump port connecting portion 3A.

  Thus, in the pilot valve device according to the third embodiment, various foreign matters (contamination) such as dust contained in hydraulic fluid discharged from a hydraulic pump (not shown) can be reduced from entering the casing 2. Thereby, since it is possible to suppress the casing 2 and the spool 20 and the like from being worn by contamination, the reliability and stability of the pilot valve device can be improved.

  In the pilot valve device according to the third embodiment described above, the case where the filter 41 is provided in the pump port connection portion 3A of the pilot valve device 1 according to the first embodiment has been described as an example. However, the present invention is not limited to this. For example, the filter 41 may be provided in the pump port connecting portion 3A of the pilot valve device according to the second embodiment.

  Moreover, in each embodiment mentioned above, the case where a pilot valve apparatus is used for the operating device for performing excavation work of a hydraulic excavator is described as an example. However, the present invention is not limited to this. For example, the present invention may be applied to an operating device that operates traveling of a hydraulic excavator, and may be applied to other construction machines such as a hydraulic crane. Moreover, you may apply to the pilot valve apparatus which operates the hydraulic actuator mounted in industrial machines other than a construction machine.

DESCRIPTION OF SYMBOLS 1 Pilot valve apparatus 2 Casing 3 Pump port 4 Tank port 5 Output port 6 Spool sliding hole 6A Damping chamber 19 Pusher 20,31 Spool 23 Passage 23A 1st passage (flow path)
23B Second passage 24 Restriction 25, 36 First switching portion 26, 37 Second switching portion 34 Spool side passage (flow path)
35 Casing side passage (flow path)
41 Filter

Claims (3)

A casing having a spool sliding hole extending in the length direction and provided with a pump port, a tank port and an output port spaced apart in the length direction of the spool sliding hole;
A spool that is displaceably provided in a spool sliding hole of the casing and communicates the output port with either the pump port or the tank port;
A pusher located on one side in the longitudinal direction of the spool and provided to be displaceable in the casing and slidably displacing the spool by an external pressing operation;
On the other side in the length direction of the spool sliding hole, a damping chamber for applying fluid pressure to the end surface on the other side in the length direction of the spool is provided, and the damping chamber is provided via a flow path having a throttle. In the pilot valve device communicating with the tank port,
The spool is provided with a first switching unit for communicating and blocking the pump port and the output port, and a second switching unit for communicating and blocking the tank port and the output port,
The pilot valve device, wherein the second switching part is provided at a position closer to the damping chamber than the first switching part. The spool includes a first passage serving as the flow path, one side communicating with the tank port and the other side communicating with the damping chamber via the throttle, and the first passage and the output port. And a second passage that can communicate with each other,
The pilot valve device according to claim 1, wherein the second passage constitutes a part of the second switching unit.   The pilot valve device according to claim 1 or 2, wherein the pump port is provided with a filter.

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